An amplifier is an electronic component that amplifies an input signal to produce an amplified output signal. A variable gain amplifier is a type of amplifier that can be set to output signals at different amplification levels. That is, a control input to a variable gain amplifier controls the level of amplification by which the amplifier amplifies an input signal. A variable gain amplifier can be characterized by an estimated gain profile that maps values of the control input to expected amplification levels of the output signal. Due to various causes, however, the actual amplification level of a signal output by the amplifier in response to a particular value of the control input is sometimes different than the expected amplification level from the estimated gain profile. For example, the estimated gain profile of the amplifier might have been imprecisely determined. As another example, the estimated gain profile might have been determined in, for example, a factory setting and thus under different operating conditions than the conditions in which the amplifier may later be used. Moreover, the characteristics, including the gain profile, of an amplifier can change during operation of the amplifier due to, for example, changing operating and ambient conditions such as temperature and the like. For such reasons, it is typically necessary to operate an amplifier with a sufficient guard band to account for such uncertainties in the estimated gain profile of the amplifier. The greater the amplification level at which the amplifier is operated, however, the more power the amplifier uses, which can affect power costs, battery life in battery powered systems, performance in code division multiple access (CDMA) communications systems, and have other adverse affects.
In some embodiments, the instant invention can estimate the gain profile of an amplifier and/or modify an estimated gain profile of an amplifier during operation of the amplifier. This can, in some embodiments, improve the precision of the estimated gain profile and thus allow operation with a reduced guard band. In some embodiments, this can reduce power costs, improve battery life, improve performance of a CDMA communications system, and/or provide other benefits.